EUDIW - iOS Library for Presentation Exchange V2.0.0

❗ Important! Before you proceed, please read the EUDI Wallet Reference Implementation project description

In a nutshell

Presentation Exchange v2 is a specification that defines:

• A way for the Verifier to describe proof requirements in terms of PresentationDefintion object
• A way for the Holder to describe submissions of proofs that allign with those requirements in terms of a PresentationSubmission

The use of this specification is mandatory by OpenID4VP

Library functionality

• As a Verifier be able to

  • produce a valid PresentationDefinition in order to be communicated to a Holder using a protocol like OpenID4VP
  • decide whether a given PresentationSubmission satisfies a specific PresentationDefinition

• As a Holder/Wallet be able to

  • parse/validate a PresentationDefition
  • to check if a claim stored in the wallet satisfies a PresentationDefinition
  • to produce a PresentationSubmission given a valid PresentationDefintion and a matching Claim

Presentation Exchange optional features supported

Feature	Status
Submission requirement	❌
Predicate	❌
Relational constraint	❌
Credential status constraint	❌
JSON-LD framing	❌
Retention	❌

Usage

import PresentationExchange

let matcher = PresentationMatcher()
let presentationDefinition = ...
let claims = ...
    
let match = matcher.match(
  claims: claims,
  with: presentationDefinition
)

switch matched {
case .matched(let matches):
  ...
case .notMatched:
  ...
}

In the resources folder there are several examples of PresentationDefintion JSON objects taken from directly from the specification

Verifier: Produce a valid PresentationDefinition

Precondition:

• Verifier should know the data model of the claim(s) that wants to be presented by the holder
• Verifier should be able to describe which formats (jwt, jwt_vc, ldp_vc etc.) and which algorithms is able to process

Library should offer a factory/builder to produce the PresentationDefinition. The resulting PresentationDefinition should

• Adhere to the data model defined in the spec (JSON Schema validation)
• Contain valid JSONPath expressions

In order to create a presentation definition just instantiate the PresentationDefinition data class which enforces the syntactic a conditional rules as defined in the specification.

Holder: Parse/Validate a PresentationDefintion

The holder should be able to verify that a JSON object is a syntactically valid PresentationDefintion:

• Adheres to the data model defined in the spec (JSON Schema validation)
• Contain valid JSONPath expressions

Dependencies (to other libs)

• JSONSchema support: JSON Schema
• JSONPath support: Sextant
• Lint support: SwiftLint
• JWS, JWE, and JWK support: JOSESwift
• Testing support: Mockingbird

References

• Presentation Exchange v2
• JSON Schema of data model